What are the common Cisco IOS show commands for troubleshooting?
show running-config, show interfaces, show ip interface, show arp, show ip route, show protocols, and show version.
The show family is read-only — it never changes the device, it just reports state — which makes it the safe first move when troubleshooting. The trick is matching the command to the layer of the problem. If a link is dead, show interfaces reveals Layer 1/2 status and error counters; if addressing looks wrong, show ip interface gives the Layer 3 detail; if traffic reaches the router but goes nowhere, show ip route shows whether a path to the destination even exists. show running-config confirms what you think is configured actually is, show arp lists the local IP-to-MAC bindings, show protocols says which protocols are up, and show version reports the hardware, memory, and licensing. Knowing which one answers which question is what turns a vague "the network is broken" into a specific, layer-by-layer diagnosis.
Common IOS show Commands:
| Command | Description |
|---|---|
show running-config |
Verifies the current configuration and settings |
show interfaces |
Verifies interface status and displays any error messages |
show ip interface |
Verifies Layer 3 information of an interface |
show arp |
Verifies the list of known hosts on the local Ethernet LANs |
show ip route |
Verifies the Layer 3 routing information |
show protocols |
Verifies which protocols are operational |
show version |
Verifies memory, interfaces, and licenses of the device |
Key insight: These commands are fundamental tools for any network administrator troubleshooting Cisco devices.
Go deeper:
Wikipedia — Cisco IOS — the CLI modes (user/privileged EXEC, config) these showcommands run in and how the OS is structured.